Functional assessment and treatment catheters and methods for their use in the lung

ABSTRACT

Lung conditions are diagnosed and optionally treated using a functional assessment catheter or a functional lung assessment and treatment catheter. A flow restrictive component is initially placed in a bronchus or lung passageway upstream from a diseased lung region. The isolated lung region is then functionally assessed through the catheter, while the flow restrictive component remains in place. If the patient is a good candidate for treatment by occlusive or restrictive treatment techniques, the flow resistive component may be left in place. If the patient is not suitable for such treatment, the flow resistive component may be removed.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/845,296 (Attorney Docket No. 20920-721.201), filed Aug. 27, 2007,which claims priority to Provisional Application No. 60/823,734,(Attorney Docket No. 20920-721.101), filed Aug. 28, 2006, andProvisional Application No. 60/828,496 (Attorney Docket No.20920-721.102), filed Oct. 6, 2006, the disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to medical methods andapparatus. More particularly, the present invention relates to methodsand apparatus for the assessment and treatment of lung diseases, such aschronic obstructive pulmonary disease, by detecting the status of thedisease and determining an appropriate treatment protocol.

Chronic obstructive pulmonary disease (COPD) is a significant medicalproblem affecting sixteen million people or about 6% of the U.S.population. Specific diseases in this group include chronic bronchitis,asthmatic bronchitis, and emphysema. While a number of therapeuticinterventions are used and have been proposed, none are completelyeffective, and COPD remains the fourth most common cause of death in theUnited States. Thus, improved and alternative treatments and therapieswould be of significant benefit.

Management of COPD is largely medical and infrequently surgical.Initially, exercise and smoking cessation are encouraged. Medicationsincluding bronchodilators and anti-inflammatories are routinelyprescribed. Pulmonary rehabilitation has been shown to improve qualityof life and sense of well being. Long term oxygen is generally reservedfor the more severely affected patients.

Emphysema is a condition of the lung characterized by the abnormalpermanent enlargement of the airspaces distal to the terminalbronchiole, accompanied by the destruction of their walls. It is knownthat emphysema and other pulmonary diseases reduce the ability of partof the lungs to fully expel air during the exhalation phase of thebreathing cycle. During breathing, the diseased portion of the lung doesnot fully recoil due to the diseased lung tissue being less elastic thanhealthy tissue. Consequently, as the airways normally held open by theelastic pull of the lungs become floppy and the diseased lung tissueexerts a diminished driving force during exhalation, the airways closeprematurely resulting in air trapping and hyperinflation.

In addition, hyper-expanded lung tissue occupies more of the pleuralspace than healthy lung tissue. In most cases, only a part of the lungis diseased while the remaining portion is relatively healthy andtherefore still able to efficiently carry out oxygen exchange. By takingup more of the pleural space, the hyper-expanded lung tissue reduces thespace available to accommodate the healthy, functioning lung tissue. Asa result, the hyper-expanded lung tissue causes inefficient breathing bycompressing the adjacent functional airways, alveolar units, andcapillaries in relatively healthier lung tissue.

Lung function in patients suffering from some forms of COPD can beimproved by reducing the effective lung volume, typically by resectingdiseased portions of the lung. Resection of diseased portions of thelungs both promotes expansion of the non-diseased regions of the lungand decreases the portion of inhaled air which goes into the lungs butis unable to transfer oxygen to the blood. Accordingly, recruitment ofpreviously compressed functional airways, alveolar units, andcapillaries in relatively healthier lung is possible resulting in moregas exchange in addition to better matching of lung and chest walldimensions. Lung reduction is conventionally performed in open chest orthoracoscopic procedures where the lung is resected, typically usingstapling devices having integral cutting blades.

While effective in many cases, conventional lung volume reductionsurgery (LVRS) is significantly traumatic to the patient, even whenthoracoscopic procedures are employed. Such procedures often result inthe unintentional removal of healthy lung tissue, and frequently leaveperforations or other discontinuities in the lung which result in airleakage from the remaining lung. Even technically successful procedurescan cause respiratory failure, pneumonia, and death. In addition, manyolder or compromised patients are not able to be candidates for theseprocedures.

As an alternative to LVRS, endobronchial volume reduction (EVR) usesendobronchially introduced devices which plug or otherwise isolate adiseased compartment from healthier regions of the lung in order toachieve volume reduction of the diseased compartment. Isolation devicesmay be implanted in the main airways feeding the diseased region of thelung, and volume reduction takes place via absorption atelectasis afterimplantation or via collapse by actively suctioning of the targetcompartment prior to implantation. These implanted isolation devices canbe, for example, self-expanding occlusive stents that prevent air flowin both directions or one-way valves that allow flow in the exhalationdirection only.

While a significant improvement over LVRS, EVR can have a limitedtherapeutic benefit when the treated region in the lung is exposed tocollateral ventilation from adjacent regions. The lungs comprise aplurality of compartments, referred to as lung compartments or lobes,which are separated from one another by a double layer of enfoldedreflections of visceral pleura, referred to as fissures. While thefissures which separate the compartments are typically impermeable, inpatients suffering from COPD, the fissures are frequently incomplete,leaving a pathway for collateral airflow or inter-lobular collateralventilation. Such collateral airflow can result in the intrusion of airinto the isolated lung compartments treated by LVR, thus reducing oreliminating the desired volume reduction.

While collateral flow to diseased lung compartments can be detected, forexample using the methods described in copending, commonly-owned U.S.patent application Ser. Nos. 11/296,591, filed on Dec. 7, 2005 (US2006/0264772A1) and 11/550,660, filed on Oct. 18, 2006 (US2007/0142742A1). While the use of these procedures can identify patentslikely to benefit from EVR procedures, the need to perform a separatediagnostic procedure prior to a therapeutic procedure is time consuming,costly, and inconvenient for the patient.

For these reasons, it would be desirable to provide alternative andimproved methods and apparatus for performing endobronchial volumereduction (EVR) and other lung therapies in an efficient and effectivemanner. In particular, it would be desirable to provide methods andapparatus which permit both the detection of collateral ventilation andsubsequent treatment of diseased lung compartments in a single protocolwhere the treatment is completed only for those patients having no or anacceptable level of collateral ventilation. At least some of theseobjectives will be met by the inventions described hereinbelow.

2. Description of the Background Art

Exemplary methods for treating diseased lung compartments by isolatingthe diseased regions are described, for example, in U.S. Pat. No.6,287,290; U.S. Pat. No. 6,679,264; U.S. Pat. No. 6,722,360; U.S. Pat.No. 7,011,094; and printed publication U.S. 2007/0005083. Methods fordetecting collateral ventilation prior to treatment of diseased lungregions are described in patent publications U.S. 2006/0264772A1 andU.S. 2007/0142742A1, the full disclosures of which have been previouslyincorporated herein by reference.

BRIEF SUMMARY OF THE INVENTION

The present invention provides improved methods and apparatus fortreating targeted lung compartments, typically diseased lungcompartments, in patients suffering from emphysema or other forms ofCOPD. The methods allow for both detecting collateral ventilation in thetarget lung compartment and for treating the target lung compartment ina single protocol, thus reducing the time and expense necessary fortreating patients and providing a more convenient and acceptable therapyfor the patient.

The methods utilize a catheter having a flow restrictive componentconnected thereto, typically at a distal end. The flow restrictivecomponent is deployed in a main bronchus which feeds the target lungcompartment while said component is connected to the catheter. While thetarget lung compartment remains isolated by the flow restrictivecomponent, a determination is made of whether collateral ventilationexists in the target lung compartment. Any of the protocols described inpublished applications U.S. 2006/0264772 or U.S. 2007/0142742, both ofwhich have been previously incorporated herein by reference, may beemployed.

If it is determined that collateral ventilation is not present in thetarget lung compartment, the flow restrictive component may be detachedfrom the catheter and left in place to effect a permanent isolation ofthe compartment to complete what is likely to be a successful LVRtherapy. If, on the contrary, collateral ventilation is found to existto a degree which would make successful LVR treatment unlikely, the flowrestrictive component will be left attached to the catheter, and thecatheter may be used to withdraw the flow restrictive element from thelung. The patient may then be treated by other therapies. By using theflow restrictive element both for the detection of collateralventilation and for the optional treatment using EVR protocols,treatment time is reduced and the patient's comfort is increased.

The flow restrictive component may be the same as or similar to manycomponents already described in the patent and medical literature. Thatis, a flow restrictive element may be intended to effect a completeblockage of flow into and out of the isolated lung compartment. Suchblocking elements may be referred to as “occlusive stents,” and aredescribed in commonly-assigned U.S. Pat. No. 6,527,761 and U.S. Pat. No.6,997,918, the full disclosures of which are incorporated herein byreference. Alternatively, the flow restrictive elements may comprise arestrictor which includes a small orifice, small diameter tube,perforated membrane, densely braided structure, perimeter channel, orother fixed-resistance element which impedes flow, but allows a low flowin both directions. Such flow-permitting restrictors are referred to as“restrictor stents,” and are described in copending application Ser. No.11/682,986, the full disclosure of which is incorporated herein byreference.

Regardless of whether an occlusive stent is used or a restrictive stentis used, it will usually be necessary that the flow restrictor providefor a flow path from the catheter to the isolated lung compartment topermit performance of the diagnostic test for collateral ventilation.The tests described in the previously incorporated patent applicationsgenerally rely on detecting flow from the isolated compartment orintroducing gas into the isolated compartment in order to determinecompliance. Thus, while used in the diagnostic or determining mode, itwill usually be necessary that the flow restrictor have the ability toallow gas flow into and/or out of the compartment.

Flow restrictive elements or components which allow for flowtherethrough can be provided in a number of ways. For example, therestrictive stents described in application Ser. No. 11/682,986 eachhave an orifice, lumen, or other flow channel present therein which canbe relied on for gas exchange in the methods of the present invention.In the case of occlusive stents, it is possible to provide for atemporary orifice or flow path therethrough which can be sealed when theflow restrictive element is detached from the delivery catheter.

The present invention further provides functional assessment catheterscomprising a catheter shaft and a flow restrictive component thereon.The catheter shaft has a distal end, a proximal end, and a centralpassage therebetween. The flow restrictive component is disposed on orat the distal end of the catheter shaft and has an expandedconfiguration and a contracted configuration.

In a first embodiment, a separate obturator is disposed in the centralpassage of the catheter shaft and is shiftable between a distallyadvanced position and a proximally retracted position. In the distallyadvanced position, the distal end of the obturator engages and elongatesthe flow restrictive component which causes the component to assume thecontracted configuration. By proximally retracting the obturator, theflow restrictive component is allowed to resume or “spring back” to itsexpanded configuration. Thus, the flow restrictive component can bedelivered to the bronchus feeding the lung compartment by firstadvancing the component in its contracted configuration with theobturator advanced and then deploying the component by retracting theobturator to allow the flow restrictive component to expand in situ at adesired location immediately upstream of the target lung compartment.

In this first embodiment, the functional assessment catheter may have apermanently attached flow restrictive element, in which case it isuseful only for performing the diagnostic function and not for releasingthe flow restrictive element to treat the patient. To use the catheterin a therapeutic situation, additional means for separating flowrestrictive element from the catheter shaft would be provided.

In a second embodiment, a functional assessment and treatment catheteris specifically designed to permit release of the flow restrictivecomponent from the catheter shaft. The flow restrictive component issecured to a distal end of the catheter shaft by a selective releasemechanism. A wide variety of suitable selective release mechanisms areavailable, including mechanical mechanisms, such as screws, lock andrelease mechanisms, spiral screw mechanisms, shape memory releasemechanisms, collets, latches, jaws, and the like. Electrical andelectromechanical release mechanisms would also be available, includingpiezoelectric detachment mechanisms, electrical heating and expansionrelease mechanisms, and the like. Additionally, magnetic releasemechanisms would be available. A variety of release mechanisms of thetype used in embolic coil release would be useful in the releasestructures of the present invention. Such release mechanisms aredescribed, for example, in U.S. Pat. Nos. RE37/117; 6,099,546;5,800,455; and 5,624,449; the full disclosures of which are incorporatedherein by reference.

In both the releasable and nonreleasable flow restrictive componentembodiments, the flow restrictive component will preferably comprise aresilient scaffold having an elastomeric covering over at least aportion thereof. Usually, the resilient scaffold comprises counterwoundhelical supports formed from stainless steel, spring steel with coating,memory polymers, nickel-titanium alloys, and the like. The elastomericcovering can be formed from a variety of polymers, including silicones,polyurethanes, polyethylenes, polyvinylchlorides, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a functional assessment catheter of the presentinvention, employing an obturator for expanding and contracting a flowresistive component.

FIGS. 2A and 2B illustrate the flow restrictive component of FIG. 1 inboth the expanded (FIG. 2A) and contracted (FIG. 2B) configurations.

FIG. 3 illustrates a functional assessment and therapy catheter of thepresent invention, where the flow restrictive component is detachableand is constrained during delivery by an outer tubular delivery member.

FIGS. 3A through 3C illustrate an exemplary release mechanism forselectively detaching a flow restrictive component from a cathetershaft.

FIGS. 4A through 4D illustrate delivery and release of the flowrestrictive component from the catheter of FIG. 3.

FIGS. 5-8 illustrate specific flow restrictive components useful withthe catheter of FIG. 3.

FIG. 9 is an anatomical diagram illustrating the lobar structure of thelungs of a patient.

FIG. 10 illustrates the trans-esophageal endobronchial placement of thefunctional assessment and therapy catheter of the present invention inan airway leading to a diseased lung compartment.

FIG. 11 illustrates the initial placement of a flow restrictivecomponent in accordance with the principles of the methods of thepresent invention.

FIG. 12 illustrates the use of the functional assessment catheter fordetermining collateral ventilation.

FIG. 13 illustrates release of the flow restrictive component into thelung passageway after it has been determined that collateral ventilationdoes not exist in the diseased lung compartment.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1, a functional assessment catheter 10 constructed inaccordance with the principles of the present invention comprises ashaft 12 having a flow restrictive component 14 attached at its distalend and a hub assembly 16 attached at its proximal end. The shaft 12will have dimensions and mechanical properties suitable fortrans-bronchial introduction into the passageways of the lung, typicallywhere the flow restrictive component 14 may be placed into the branchingbronchii of the lung and advanced to locations in the main bronchusfeeding a target lung compartment. Usually, the shaft will comprise abraid-reinforced polymer, such as a polyvinylchloride, apolytetrafluoroethylene (PTFE), a polypropylene, a polyethyleneterephthalate (PET), a polyurethane, a polyurethane/polycarbonatemixture, or any one of a variety of other suitable polymers. In aspecific embodiment, a catheter shaft will comprise a relatively softdistal region 18 and a relatively harder proximal region 20. Forexample, the distal region can be formed from a 55D durometerpolyethylene block polyamide (PEBAX) and the proximal region 20 can beformed from a 72D durometer PEBAX.

The flow restrictive component 14 will normally be in an expandedconfiguration, as shown in FIGS. 1 and 2A, but may be axially elongatedin order to assume a contracted or narrow diameter configuration, asshown in FIG. 2B. The component 14 will typically comprise a scaffoldstructure 40, typically formed from counterwound helical elements,covered at least partially by an elastomeric covering 42. The individualhelical elements will be formed from an elastic material, typically anelastic metal but optionally a shape memory polymer. Suitable elasticmetals include stainless steel, spring stainless steel, nickel-titaniumalloy, and the like. In an exemplary embodiments, the elastic elementsare made from 0.125 mm nitinol wires counterwound into a braid. Theindividual nitinol wires are joined at a distal end by end cap 44 andare connected at their proximal ends to the distal end of the distalregion 18 of the shaft 12. Alternatively, the scaffold structure couldbe made by chemically etching a thin layer of a suitable elastic metaland forming into the shape of the restrictive component. The membranecan be made from any of the materials described earlier, and in theexemplary embodiment will be formed from a silicone formed over theproximal portion of the scaffold 40 and extending over the mid-sectionof the scaffold, leaving a distal region 46 of the scaffold open. Whilethe distal region is open, the mid-section of the flow restrictivecomponent 14 will be able to engage the interior of the bronchus inwhich it is expanded in order to form a tight seal, at least while theflow restrictive component 14 remains attached to the shaft 12.

In the particular embodiment illustrated in FIGS. 1, 2A, and 2B, theflow restrictive component 14 is intended to remain fixed to the shaft12, so the catheter 10 is intended only for assessment, not for therapy.It will be appreciated that this structure could be modified, or aseparate releasing device could be provided in order to detach the flowrestrictive component 14 from the shaft in order to leave the componentin place should the patient be a good candidate for therapy. Otherembodiments of the catheter, described hereinafter, are shown withspecific detachment means for use in both diagnostic and therapeuticapplications.

An obturator assembly 30 is provided in order to elongate and constrictthe diameter of the flow restrictive component 14. The obturatorassembly 30 comprises a flexible rod 32, typically a coiled wire formedfrom a metal or semi-rigid plastic material. Suitable metals includestainless steel, titanium, nickel-titanium alloy, or any other metal ofthe type conventionally used in construction of medical guidewires.Metal shafts may be coated with PTFE or other material in order toenhance the lubricity as it is introduced through a lumen of the shaft12 into the interior of the flow restrictive component 14. A distal tip33 engages the end cap 44 of the flow restrictive component 14, as bestseen in FIG. 2A. By axially advancing the rod 32, the end cap 44 istranslated distally, thus axially elongating the flow restrictivecomponent 14 and reducing its diameter, as best seen in FIG. 2B.Conveniently, an advancement actuator 34 may be connected to a proximalend of the rod 32. As illustrated in FIG. 1, the actuator 34 maycomprise a connector 36 which is mountable on a luer or other fitting 17on proximal hub 16. Once the actuator 34 is attached to the hub 16, aplunger 38 may be depressed in order to advance the rod 32 in thedirection of arrow 48 in FIG. 2B. Optionally, a detent or other lockingmechanism may be provided in the actuator 34 in order to hold the flowrestrictive component 14 in its narrow diameter configuration duringintroduction into the bronchii. By releasing the plunger 18, the springforce in the flow restrictive component 14 will push the rod 32proximally and allow the component to reassume its expanded or largediameter configuration within the main bronchus leading to the targetlung compartment.

Referring now to FIG. 3, a functional assessment and therapy catheter 50will be described. The catheter 50 differs from the functionalassessment catheter 10 described previously in that it is adapted toselectively release a flow restrictive component 54 from a distal end ofa catheter shaft 52. In particular, a release mechanism 58 is formed orotherwise provided at a proximal end of the flow restrictive component54. The release mechanism 58 may take any of a wide variety of forms,including mechanical, electrical, chemical (e.g., dissolvable), orcombinations thereof. The release mechanism 58 will retain the flowrestrictive component 54 firmly on the distal end of the shaft 52 untilsuch a time as it may be desired to release the component within abronchii. While the flow restrictive component 54 remains attached tothe shaft, a flow path will remain between a lumen in the shaft 52 and apassage, lumen, open interior, or other provision within the flowrestrictive component which permits gas exchange between the lumen andthe shaft 52 and a distal region of the flow restrictive component 54.The ability to permit gas exchange through the catheter shaft 52 andflow restrictive component 54 is desirable to allow performance ofcollateral ventilation or other diagnostic procedures while the flowresistive component 54 is expanded within the bronchii and stillattached to the catheter shaft 52.

An exemplary release mechanism 158 for selectively detaching a flowrestrictive component 154 from a catheter shaft 152 is illustrated inFIGS. 3A through 3C. The release mechanism 158 comprises a collar 153attached at a proximal end of the self-expanding flow restrictivecomponent 154. An attachment ball 151 projects from a proximal end ofthe sleeve 153. Both the attachment ball 151 and the sleeve 153 have aninternal passage 157 which permits air flow through the releasemechanism 158 so that air or other gases may be exchanged from thecatheter shaft 152 through an open aperture 159 at a distal end of theflow restrictive component 154. The attachment ball 151 is received inan opening 155 (FIG. 3B) formed in a side of the shaft 152 and is heldin place by a wire or other element having a tapered distal end which iswedged on a side of the ball opposite to the opening 155. So long as thewire 156 remains in place, as shown in FIG. 3A, the ball will be firmlyheld within the opening 155 and the flow restrictive component 154 willremain attached to the catheter shaft 152. The flow restrictivecomponent 154 may be released, however, by withdrawing the wire 156, asshown in FIG. 3B, to allow the attachment ball 151 to be freed from theconstraint of the hole 155. In this way, the flow restrictive component154 may be completely released from the catheter shaft 152, as shown inFIG. 3C.

Usually, a separate delivery sheath 60 will be provided for facilitatingdelivery of the flow restrictive component 54 of the catheter 50. Thesheath 60 will have a diameter 60 suitable for introduction into thetarget bronchii, typically having an outer diameter in the range from 1mm to 3 mm. The flow restrictive component 54 will be radiallyconstrained and introduced through an interior lumen of the deliverysheath, simply by pushing the shaft 52 distally so that the constrainedflow restrictive component 54 is advanced through the sheath 50 as shownin FIG. 4A. Initially, the flow restrictive component 54 will be fullycontained within the sheath 60. As the shaft 52 continues forwardadvancement, the flow restrictive component 54 will emerge from a distalend of the sheath 60, as shown in FIG. 4B. Upon further advancement, theflow restrictive component 54 will be fully released from the sheath, asshown in FIG. 4C. After performing a desired assessment of collateralventilation or other lung compartment characteristic while the flowrestrictive component 54 remains inflated and the lung compartmentisolated, the flow restrictive component may be selectively released byactuating mechanism 58, as shown in FIG. 4D. After release, flowrestrictive component 54 may be fully closed in order to provide fortotal occlusion of the bronchii in which it has been deployed.Alternatively, a smaller controlled flow path may remain through theflow restrictive component 54 in order to provide for controlledatelectasis or hypoxic pulmonary vasoconstriction (HPV), as described incopending application Ser. No. 11/682,986, the full disclosure of whichhas been previously incorporated herein by reference.

Specific examples of flow restrictive elements suitable for permittingcontinued air exchange with the isolated lung compartment and controlledatelectasis and/or HPV are illustrated in FIGS. 5-8.

FIG. 5 illustrates a flow restrictive component 160 in which a housing162 houses a funnel-shaped (or hourglass-shaped) diaphragm 164 whichprovides a gas flow orifice 166 in the center of the diaphragm. Distaland proximal apertures 168 and 170, respectively, allow air flow intoand out of the housing 162, and the tapered orifice 166 defined by thediaphragm 164 restricts the flow. The diameter of the orifice 166 can beselected to provide a desired flow resistance. The housing 162 can havea uni-body construction or be a wire braided structure encapsulated withsilicone or other elastomere. The diaphragm can be a flexible siliconematerial or other elastomere in order to facilitate compressibility ofthe restrictor 160 for insertion into the lung via a delivery sheathlumen.

FIG. 6 illustrates flow restrictive component 170 in which a gas flowtube 172 is axially aligned in a housing 174. Construction of thehousing 174 can be similar to any of the concepts previously described.The gas flow tube 172 can be constructed of any tubular material,preferably being a flexible polymer. Flexibility is advantageous since aflexible tube will facilitate insertion into the lung. The housing 174can have any of the constructions described previously.

FIG. 7 is a cross-sectional view of a flow restrictive component 130 inwhich a housing 132 includes a gas flow orifice tube 134 on its distalend 136. The housing can have a “uni-body” construction, typically beingmolded or cast from silicone or another biocompatible elastomer. In someinstances, the housing 132 can have composite construction of wire framewith silicone membrane coating, or be formed from a variety of materialsand construction methods. It can be collapsible and self expanding for acatheter based delivery. In other designs, the flow restrictivecomponent can be malleable to allow plastic deformation and expansion bya balloon or other expandable deployment on the delivery catheter.

FIG. 8 illustrates a flow restrictive component 140 in which a housing142 comprises a plurality of windows 144 in a wall of a distal section46 in order to permit gas flow in and out of the housing. An orifice 148at the opposite proximal end completes the gas flow path such that thedevice restricts but does not obstruct gas flow. As with previouslydescribed embodiments, the housing 142 can have a uni-body constructionor comprise a wire frame with silicone or other membrane covering. Itcan be either collapsible and self expanding or balloon expandable.

Referring now to FIG. 9, the respiratory system of a patient starts atthe mouth and extends through the vocal cords and into the trachea whereit then joins the main stem bronchi B which leads into the right lung RLand the left lung LL. The bronchi going into the right lung divide intothe three lobar bronchi which lead into the upper lobe RUL, the middlelobe RML and the lower lobe RLL. The lobes of the right lung include atotal of ten segments (three in the RUL, two in the RML, and five in theRLL) which are discrete units of the lung separated from each other by afibrous septum generally referred to as a lung wall. The left lung LLincludes only an upper lobe LUL and a lower lobe LLL, where theindividual lobes include four to five segments each.

Each lung segment, also referred to as a bronchopulmonary segment, is ananatomically distinct unit or compartment of the lung which is fed airby a tertiary bronchus and which oxygenates blood through a tertiaryartery. Normally, the lung segment and its surrounding fibrous septumare intact units which can be surgically removed or separated from theremainder of the lung without interrupting the function of thesurrounding lung segments. In some patients, however, the fibrous septumseparating the lobes or segments may be perforate or broken, thusallowing air flow between the segments, referred to as “collateralventilation.”

Use of the delivery sheath 60 for placement of the flow restrictivecomponent 54 in accordance with the principles of the present inventionshown generally in FIGS. 10-13. The sheath 60 is advanced through themouth, down through the trachea T and through the main bronchus into theleft lung LL. A distal end 62 of the sheath 60 is advanced into the leftlung LL, and further advanced to an airway or bronchus which feeds adiseased lung region DR. The sheath 60 may be introduced through themain bronchus B and into the left lung LL without the use of abronchoscope or other primary introducing catheter, as illustrated inFIG. 10. Alternatively, the sheath 60 may be introduced through aconventional bronchoscope (now shown) which is positioned in the mainbronchus B above the branch between the right and left lungs. Stillfurther alternatively, the sheath 60 may be introduced into the lungthrough a scope, such as a visualizing endotracheal tube (not shown)which is capable of being advanced into the branching bronchii of thelung and which may be advantageous since it facilitates positioning ofthe sheath 60 at the desired airway leading to the target diseased lungsegment. Construction and use of a visualizing endotracheal tube istaught, for example, in U.S. Pat. No. 5,285,778, the full disclosure ofwhich is incorporated herein by reference.

After the distal end 62 of the delivery sheath 60 has been positioned inthe main airway or bronchus which feeds the diseased lung region DR, thesheath may be optionally immobilized by inflating a balloon or cuff 64at or near the proximal end of the sheath 60. After immobilizing thedistal end of the sheath, the catheter shaft 52 of catheter 50 may bedistally advanced in order to deploy the flow restrictive component 54into the feeding bronchus FB leading to the diseased lung region DR, asshown in FIG. 12. Once the flow restrictive component 54 is deployed, adiagnostic procedure for determining the extent and/or treatability ofthe disease may be performed, generally as described in previousapplication Ser. Nos. 11/296,951 and 11/550,660, the full disclosures ofwhich have previously been incorporated herein by reference. If it isdetermined that the patient is suitable for treatment by an occlusive orflow restrictive protocol, the flow restrictive component 54 may bereleased and implanted in the feeding bronchus FB, as shown in FIG. 13.If, however, the patient is determined to be unsuitable for suchtreatment, the flow restrictive component 54 may be removed from thefeeding bronchus FB, typically by retraction into the delivery sheath 60and subsequent removal of the sheath from the lung.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, and equivalentsmay be used. Therefore, the above description should not be taken aslimiting the scope of the invention which is defined by the appendedclaims.

What is claimed is:
 1. A functional assessment catheter for the lungs,said catheter comprising: a catheter shaft having a distal and aproximal end, and a central passage therebetween; a flow restrictivecomponent disposed at the distal end of the catheter shaft, wherein theflow restrictive component has an expanded configuration and acontracted configuration; and an obturator disposed in the centralpassage and shiftable between a distally advanced position where itengages and elongates the flow restrictive component to cause thecomponent to assume the contracted configuration, and a proximallyretracted position where it allows the flow restrictive component toshorten and return to the expanded configuration.
 2. A functionalassessment catheter as in claim 1, wherein the flow restrictivecomponent comprises a resilient scaffold and an elastomeric covering. 3.A functional assessment catheter as in claim 2, wherein the resilientscaffold comprises counter wound helical supports.
 4. A functionalassessment catheter as in claim 1, wherein a flow path is formed throughthe flow restrictive component so that gas may flow through the cathetershaft and through the flow restrictive component.
 5. A functionalassessment catheter as in claim 4, wherein the flow path comprises thecentral passage and an opening in a distal side of the elastomericcovering.
 6. A functional assessment and treatment catheter for thelungs, said catheter comprising: a catheter shaft having a distal end, aproximal end, and a central lumen therethrough; and a flow restrictivecomponent releasably secured to the distal end of the catheter shaft,said flow restrictive component having an expanded configuration forsealing to an inner wall of a lung passage and a contractedconfiguration to permit positioning within the lung passage; wherein thecatheter shaft and flow restrictive component together permit gasexchange therethrough with a lung compartment distal to the flowrestrictive element while the flow restrictive element is expandedwithin a main bronchus leading to said lung compartment.
 7. A functionalassessment and treatment catheter as in claim 6, further comprising anobturator disposed in the central passageway, and shiftable between adistally advanced position where it engages and elongates the flowrestrictive component to cause the component to assume the contractedconfiguration, and a proximally retracted position where it allows theflow restrictive component to shorten and return to the expandedconfiguration.
 8. A functional assessment and treatment catheter as inclaim 6, further comprising a constraining structure configured to slideover and radically constrain the flow restrictive component.
 9. Afunctional assessment catheter as in claim 6, wherein the flowrestrictive component comprises a resilient scaffold and an elastomericcovering.
 10. A functional assessment catheter as in claim 9, whereinthe resilient scaffold comprises counter wound helical supports.
 11. Afunctional assessment catheter as in claim 6, wherein a flow path isformed through the flow restrictive component so that gas may flowthrough the catheter shaft and through the flow restrictive component.12. A functional assessment catheter as in claim 11, wherein the flowpath comprises the central passage and an opening in a distal side ofthe elastomeric covering.